METHODS OF CONTROL. 13 



and is, as a rule, the most rapid, and the locations are likely to be of the 

 greater service and distributed most uniformly. It can be used eco- 

 nomically where the country presents more or less relief, and where 

 points for location, either natural or artificial, exist in sufficient numbers 

 and are well distributed. These conditions are satisfied almost every- 

 where in the western mountain regions, where mountain peaks, summits 

 of hills, plateau points, buttes, etc., furnish an abundance of natural 

 points for stations and locations. It can be used, to a considerable 

 extent, though not with the same ease or economy in the Appalachian 

 mountains; but in this region it is necessary to supplement it extensively 

 by traverse lines, especially in tracing the courses of streams in the valleys. 

 It can be used, too, in the hill country of New England, where objects of 

 culture, such as churches, houses, etc., furnish an abundance of signals. On 

 the other hand, throughout the whole extent of the Atlantic and the Gulf 

 plains, where the country is level or nearly so, and is covered with forests, 

 the traverse method of surveying must be resorted to. This is a, country 

 devoid of sharp natural objects, a country in which extended views can not 

 be obtained. The only economical way, therefore, of proceeding, is, start- 

 ing from some point located by the triangulation, to carry a line of stations, 

 connected together by distance and direction measurements, until the line 

 checks upon a second triangulation point. For many reasons, this method 

 of obtaining locations is inferior to the former. It is inferior not onlv in 

 accuracy, but in the facilities which, as carried out, it affords for sketching 

 the country, and it should be so regarded, and should be adopted only when 

 it becomes necessary, or when the former method can not be applied eco- 

 nomically. For convenience, traverse lines are generally run along the 

 roads or trails, and thus the best points for commanding views of the country 

 are avoided rather than sought. Being practically confined to the roads, 

 there is danger that the topographer neglects, in a greater or less measure, 

 the areas lying between them. On account of the errors incident to run- 

 ning a traverse it is necessary that, in this class of work, frequent locations 

 be made by triangulation for checking and thereby eliminating its errors. 

 The locations dealt with in the above table fall into one or the other 

 of these two classes. Locations by triangulation are of much greater value 



